🥇 Anatomía del MESENCÉFALO 1/3. (Cerebro Medio) ¡Explicación Fácil!

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Welcome to a new anatomical video from your favorite anatomy channel, easy anatomy by Juan José Sánchez. Today I bring you a video of the midbrain, we already leave the brain behind, we already leave the brain behind, today we will talk about the midbrain also known simply as the midbrain, this is a structure that anatomically is small compared to the volume of the forebrain, but without However, I divided it into three videos because there is midbrain one, midbrain two and midbrain three, in this scheme that was also shown in the brain video, in the brain generalities one; Let's see that we divide the large brain, which we mistakenly call the brain, into three portions. We are talking about a forebrain also called the prosencephalon, okay?

a mesencephalic midbrain which is let's say our protagonist today and then a posterior brain also called rhombencephalon, the prosencephalon in turn called forebrain is divided into a telencephalon and a diencephalon, all the videos of telencephalon and diencephalon can be found on the channel , yes approximately they are like 15, 16 in total maybe approximately 17. Today we are going to talk about the midbrain, which has no subdivisions, it is just called the midbrain and that's it, okay? So now this is already known that it will be made up of three videos, mesencephalon one, mesencephalon 2 and mesencephalon 3 and then we will talk about the rhombencephalon which is the posterior brain that in turn is divided into metencephalon and mylencephalon, I will gradually go uploading all these videos that are also ready, only they are going to be uploaded in gradual order to finish with this entire region of the brain and finally get into the spinal cord.

Ok, without further ado, let's talk about this midbrain, see that it really is a small structure, it is divided into two large portions which are the cerebral peduncles and the quadrigeminal plate, this quadrigeminal plate in turn forms a pair of superior colliculi and a pair of inferior culiculi and then we will talk about the sylvian aqueduct, which is not in itself a physical structure of the midbrain but rather a cavity passing through practically everything, let's say the structure of the midbrain. So in this installment of midbrain 1 we will talk about the generalities and relationships, in the video midbrain 2 we will touch more on the parts, we will talk about how the quadrigeminal plate is formed and how the structure of the peduncles is formed and in the video midbrain 3 we will talk only from the central cavity that runs through the midbrain, which is the famous aqueduct of the midbrain, also called the sylvian aqueduct. Very good, then well this midbrain that here is in green and I'll shade it in a slightly brighter green is a structure that is found in the center of the brain but in the lower part, let's say, it is important to know that this midbrain together with The structures of the hindbrain , specifically which ?

However, there are others who maintain that the diencephalon is part of the brainstem, so in this case if I added the diencephalon as part of the brainstem then the diencephalon would be the most superior part of the brainstem, however we are going to leave it with the classic connotation as that The midbrain is the most superior part of the brain stem, so practically it will be arranged between two structures, it will be joining the bridge of the rhombencephalon, specifically the metencephalon with the diencephalon of the forebrain or prosencephalon, okay? It is a structure that is between the two. Very well, let's see that its longitudinal axis that goes from top to bottom is not completely vertical but rather goes more or less obliquely from anterior to posterior and from top to bottom.

Why do they call this the brainstem? because it looks like the stem of a tree, you see the brain and the branches look leafy, let's say the leaves of a tree and this looks like the stem of the tree, that's why it was given the name brainstem, very good, the previous part of the midbrain is free and quite visible when we see it from the anterior and inferior, especially the lower front, but the posterior part is largely covered by the cerebellum, so in the posterior part to study it I have to dissect the cerebellum or simply do cuts as well as this sagittal to be able to more or less study the posterior part of the midbrain, this is an anterior view to locate them, that this is the spinal cord, this is the medulla oblongata, this is the bridge, and up here we see the peduncles of the midbrain, which is what What can be seen from the previous part, okay? See it again here how the free anterior part corresponded to this and the posterior part covered by the cerebellum; We are going to see that the place occupied by the midbrain is the place where the incisura of the tentorium of the cerebellum is, remember that the tentorium cerebellum separates the cerebellar fossa from the posterior cranial function of the most superior part, that is, it separates, divides the posterior cranial fossa, that is the tentorium cerebellum, then there is a gap, let's say called the incisura of the cerebellum, where the brain stem connects with the higher structures and that gap is what is called the incisura of the tentorium cerebellum precisely.

That level coincides with the midbrain, we see it from above, all of this is the tentorium of the cerebellum, all we see downwards is the cerebellar fossa, well towards here rather and this is the place where the midbrain would more or less be, see that It is, let's say, adjacent to that notch of the tentorium of the cerebellum. What parts will this midbrain have, roughly speaking? well first we have more towards anteriorly the famous cerebral peduncles that we will talk about or develop in the video of midbrain two and towards posteriorly the quadrigemic lamina that we will also talk about and develop in the video of midbrain 2, finally the central cavity well there we see in this sagittal cut forward the peduncle, backwards the quadrigeminal plate and we see centrally the aqueduct of the midbrain which I remind you that we will talk about it in the midbrain video 3.

We are going to talk then about the limits, later about the relationships of the midbrain, but before Don't miss out on the video [Music] ok, subscribe to the channel down here where you see that it says subscribe, click on it and you will automatically be subscribed to all the videos on it. Well, when we talk then about the limits of the midbrain we are going to see that at the lower anterior limit we see a fairly framed sulcus that separates it from the pons of valor, that is the pontomesencephalic sulcus, pontomesencephalic sulcus, this sulcus is important because well We are going to see in the other sheet what structures emerge from that sulcus, we are going to see that for its part the superior antero sulcus that would join the cerebral peduncles upwards as at the base of the brain is imprecise, it does not have an edge as such and it is practically loses in the adjacencies of the anterior perforated substance, it is difficult to delimit it, however the superior lateral or lateral superior limits as I put them here are given by the optic tracts that come more or less from anterior bordering towards the posterior part, when we see a vision posterior of the midbrain we see that the posterior limits are actually quite imprecise, however, if more or less you can denote that the quadrigerminal plate is thus more or less separated from the thalamus and the pineal gland and downwards more or less separated from the quadrigeminal plate of the let's say peduncles of the midbrain, which would be those that are here, but the place where the posterior, inferior and posterosuperior limits are in fact with that of the midbrain with the adjacent structures is quite imprecise. Well, what relationships is this midbrain going to have?

Let's start with the previous relationships. First, towards the whole, well, really inferior, we're going to see the interpeduncular fossa. We're going to develop this fossa in the video of midbrain 2, but more or less the fossa.

which is formed between the cerebral peduncles to the sides, down here the pontomesencephalic sulcus, up through the optic tracts and through the optic chiasm, this region that you see here, that gap, that is the interpeduncular fossa, it is quite a relationship. Importantly, it is good that we are going to see the emergence of the third cranial nerve, which is the common oculomotor nerve at the level of the pontomesencephalic sulcus in the lowest part of that interpeduncular fossa. Let's see what is here, you will also find the posterior perforated substance as a relation anterior to those cerebral peduncles, important in the name of cerebral peduncles because when you study the cerebellum and the structures of the hindbrain you will realize that there are some peduncles cerebellar, so to differentiate it we have to talk about cerebral peduncles when we refer to the midbrain and cerebellar peduncle when we do not want to refer to those of the cerebellum, okay?

Very well, let's see that there we are going to find some arterial vascular structures, first the posterior cerebral artery that you see that surrounds everything, let's say the structure of the midbrain from medial to the lateral, the superior cerebellar artery will also do the same , of course there is other structures there that are at the level of the interpeduncular fossa but that we will talk about when we name the interpeduncular fossa, these are the let's say thick relations, the large relations, we will also see that if it is anterior there is a structure, a cavity of a cistern by where the cerebrospinal fluid passes called the interpeduncular cistern, which you see would be more or less between the peduncles and the anterior region where the empty portion of the occipital and the quadrilateral lamina of the sphenoid are located, which are not seen in the image but are supposed to be more or less here. Ok, let's look at the relationships of this mesencephalon posteriorly , first well let's go to the tentorium of the cerebellum that separates it from the occipital lobe of the brain, from the telencephalon specifically, let's see what is located centrally in that posterior part, what you see here in the background They are the colliculi, remember that this is a superior view, here we see the colliculi and here we see the great cerebral vein, in this sagittal type section, we see the great cerebral vein again and we see that it practically goes into that space posterior to the midbrain, the splenium or labrum of the corpus callosum, also that entire cavity that we see there that is between the cerebellum in the posterior part of the midbrain, the posterior part of the epithalamus, that cavity is the quadrigeminal or quadrigeminal cistern, while this one in front remembers What was called the interpeduncular era, look at this image of the cisterns, how the famous quadrigeminal cistern is denoted as the posterior relationship of the midbrain, okay? laterally we are going to see that the parahippocampal gyrus is found at the base of the brain, practically the lateral region of that midbrain, here you can see the peduncles very well, this is a lower view, we see more or less the lap of the corpus callosum, here we see the quadrigeminal plates, this is the sylvian aqueduct, then the parahippocampal gyrus would be more like a lateral relationship, in fact it covers a large part of the lateral part of the midbrain and let's say this lateral space, remember that the cistern that is here is from the quadgerminal cistern at this level, but this cistern that would be here lateral to the midbrain is called the cisterna ambiens, well, I will dedicate a video at any time to talk about the cisterns, but I want you to know that this ambiens is the lateral relationship of this midbrain.